By Dr Jane Varney
Let’s start with prebiotics. A prebiotic is a type of fibre that passes through the gastrointestinal tract undigested and stimulates the growth and/or activity of certain ‘good’ bacteria in the large intestine. While all prebiotics are considered ‘fibre’, not all fibre has prebiotic effects. Because certain FODMAPs have prebiotic effects, namely fructans and galacto-oligosachairdes (GOS), a low FODMAP diet restricts intake of prebiotic fibres.
This is one of the reasons why a low FODMAP diet is not considered a lifetime diet and why the rechallenge phase is so important. Indeed, a prebiotic rich diet is considered a healthy diet for the general population (without IBS). Diets rich in prebiotic fibres may encourage a healthy balance of gut bacteria, potentially benefiting digestion, the absorption of minerals and immune system function.
Probiotics on the other hand, are live microbial food supplements that feed on prebiotics. Common varieties include lactobacilli or bifidobacteria. Probiotics are available in a number of forms: they are found naturally in some yoghurts and fermented milk, they are sometimes added to infant formula and they are available as dietary supplements.
Probiotics may play a role in gut health, by inhibiting the growth of pathogenic (disease causing) bacteria, assisting in the digestion and absorption of nutrients, contributing to short chain fatty acid production and maintaining a healthy immune system.
There is some evidence that probiotics can help with IBS symptoms, but this may vary depending on which probiotic preparation is used. Our advice is to try one management strategy at a time. Commence a low FODMAP diet first and if you have not achieved good symptom control after 2-6 weeks on the diet, then discuss other management strategies with your dietitian, including the possibility of introducing probiotics.